DSLR vs Mirrorless Camera

Like any other technologies, the equipment being used in photography have been evolving slowly and steadily. From analog vs digital, today’s discussions go around DSLRs vs Mirrorless cameras. So in this post, I am attempting to shed some light on some of the key differences between DSLRs and Mirrorless cameras and help you in making your decision.

Construction

The primary difference in construction of DSLRs and Mirrorless cameras is the presence and absence of the “main mirror” or the “mirror box” respectively. In DSLRs, after light passes through the lens, the light is reflected towards the “penta prism” or the “penta mirror” which totally internally reflects the light and sends it outwards towards the viewfinder (where we place our eye). Whereas in case of mirrorless cameras, there are no mirror box and penta mirror. Light rays can directly strike the sensor after passing through the lens.

Points to note regarding the construction of DSLR and Mirrorless cameras:

Absence of mirror box and penta prism significantly reduces the size and weight of the mirrorless camera bodies. Smaller body size does not necessarily mean smaller sensor. A full frame mirrorless camera can roughly be the same size of a DSLR with APSC sensor. So don’t judge by the size.

Viewfinder in DSLRs are optical so you do not need to turn the camera “ON” to see through it while the viewfinder in mirrorless are electronic so you cannot see anything through the viewfinder in mirrorless cameras unless you turn the camera “ON”.

High quality penta-prisms are very expensive. Hence mirrorless cameras can save cost and use it elsewhere during the manufacturing process.

Everytime the shutter is clicked to take the picture, the mirror box in DSLRs have to move up to make way for the light to strike the sensor. This causes a temporary black-out in the optical viewfinder of the DSLRs. This is not the case in case of mirrorless.

The continuous movement of the mirror box in DSLRs also cause vibration in the camera which can lead to small amount of blur in the photos. The movement also leads to mechanical wear and tear of the camera thus reducing the camera’s life.

Viewfinders in DSLRs and Mirrorless cameras

DSLRs have optical viewfinders and need to power to work. The ambient light plays the most important role in deciding what you see through the optical viewfinder of the DSLRs. If it is dark, looking through the viewfinder can be very difficult (and impossible and useless in some extreme cases). In such cases, it becomes very challenging for a photographer to compose while looking through the viewfinder.

On the other hand, mirrorless cameras are equipped with electronic viewfinder (EVF). They are electronic displays which project the output being fed to it by the camera’s sensor. This has certain advantages over the traditional optical viewfinders:

Any changes in camera settings that you make will be immediately visible through the viewfinder. For example: if you change the aperture, ISO or shutter speed, the output in the EVF of the mirrorless cameras will change accordingly and show you how your final photo will come out. They call it as WYSIWYG (What You See Is What You Get) feature. This is impossible with the optical viewfinder of the DSLRs.

Composing in dark and challenging conditions is a breeze with EVF. Bump up the ISO or lower down the aperture value, or slow down the shutter speed and the EVF will show you what your eyes struggle to see. This is one of the best feature that I personally like of the mirrorless cameras.

EVF can not only be used to see what you are taking photos of, but they can also be used for playback. This is great if you do not want others around you to see your composition and since the EVF is usually bright, it comes in handy during bright and sunny days. Along with playback, you can also browse through the menu system via the EVF. How cool is that?

Here is a short view which highlights the benefits of EVF over OVF

There is however one drawback of the EVF system i.e. they need power to operate and you might be surprised to know that the EVFs tend to use a little bit MORE power than the big LCDs on the camera’s back. This can be due to the fact that they are brighter and have higher resolution compared to the LCD screens.

Focusing system

In DSLRs, we observed earlier that the light entering through the lens is reflected upwards towards the pentaprism. However, it is important to understand that a small portion of that light is reflected downwards towards an Autofocus (AF) sensor. It helps the camera decide where to adjust the lens to achieve focus. But due to the lack of mirror in a mirrorless camera, the engineers had to come up with a work around so they placed the AF system right on top of the sensor. Because of this, mirrorless cameras have a certain advantage over the DLSR AF system:

Mirrorless cameras can autofocus equally fast while viewing through the viewfinder or the LCD screen. If you try auto focusing in live view with a DSLR, you will notice that the camera will struggle. DSLRs are quick in focusing through the viewfinder but live-view absolutely kills them.

Features such as object tracking, eye tracking are highly optimised in mirrorless cameras due to the fact the AF sensors are right on the sensor itself.

For critical jobs, it may be necessary to calibrate your lens with your DSLR body. But this is redundant for mirrorless cameras and is unnecessary.

Mirrorless cameras have a feature called focus peaking which greatly assists you while focusing manually. These cameras can highlight areas in focus by using colored lines.

Here is a short video which highlights the mirrorless focusing features such as Manual focus assist and focus peaking.

Battery Life

The compact size of the mirrorless cameras means that they accomodate smaller size batteries. And it is not helped by the fact the viewfinder needs a power source to work and also consumes greater power than the LCD screen. This is the reason why today most of the mirrorless cameras are still inferiori to DSLRs in terms of battery life. If you are serious about your work using a mirrorless camera, then it is highly recommend that you carry some spare batteries. However, a feature in mirrorless cameras is that you can recharge the batteries using a powerbank. This is specially useful when you out trekking where there is no or very limited access to electricity.

With the recent launch of the Sony A9 in Q2 of 2017, Sony were able to cram more battery power with a slightly larger battery. They claim some 600 shots with it but all the reviews have suggested shooting over more than 1500 shots and still having some battery power left. So may be there is hope for better battery life with mirrorless cameras.

Adapting non-native lenses

Let’s understand flange focal distance (FFD). For details, you can visit the link from Brian Smith. For basic understanding, flange focal distance is the distance between the camera sensor and the lens mount.

In case of DSLRs, the presence of a mirror-box in between the camera sensor and the lens mount means that the FFD is greater than in case of mirrorless cameras where there is no mirrorbox. So, we can use adaptors in mirrorless cameras which mimics the greater flange distance like in case of DSLRs. This will allow the lenses of DSLRs to form a image circle around the camera sensor of the mirrorless camera like they would do in DSLRs. This is why we can see users adapting their high quality Leica, Canon and Nikon glasses on Sony and Panasonic mirrorless bodies.

However, the reverse is not possible. Mirrorless bodies are designed to work on short FFD. The greater FFD in DLSRs means that the image circle produced by a lens designed for a mirrorless body will not be able to cover the entire sensor of the DSLRs. This will result in vignetting and loss of quality. Therefore we have an added advantage of adapting non-native lenses in mirrorless but such is not the case for DSLRs.

However do keep in mind that adapting non-native lenses onto mirrorless bodies will have some pitfalls.

Autofocus performance of adapted lenses will drastically drop.

EXIF data may not be written to the file.

If you do not have a proper adaptor, you will not be able to control the aperture setting of your lens.

There have been many cases of adaptors freezing the camera system. In such cases, you may periodically need to remove the lens and the adaptor and reboot the camera.

Some adaptors will not allow you to focus on infinity. This will drop your focusing range.

Good adaptors don’t come in cheap. Something like the Metabones mark IV Canon to Sony adaptors costs USD 399 at the time of writing this article.

I take this feature of adapting lenses more as a benefit that I would never take advantage of. If you are a video shooter using manual focus or someone who shoots manual focus, this feature coupled with the focus peaking feature would be a gem.

I hope I was able to shed some light on the basic differences between DSLRs and mirrorless camera systems. In case you have any questions, feel free to let me know by commenting below.